Dispensers of fluid products are known, which close on a container of a fluid product to be dispensed and, therefore, which also serve the function of closing cap for said containers.
Known dispensers comprise a variable volume dosing chamber for aspirating and subsequently dispensing a portion of the fluid product from the container.
In detail, when the volume of the dosing chamber is reduced, the overpressure thus produced expels outwards the portion of fluid portion contained therein, whilst when the volume of the dosing chamber is increased the vacuum thus created aspirates a subsequent portion of product from the container to the dosing chamber. Appropriate check valves regulate the flows described above.
Known dispensers comprise a closing ring nut able to be associated to a neck of the aforementioned container and a dispensing head slidably associated to the ring nut and able to be actuated manually by a user to obtain the dispensing of the product.
The dosing chamber is obtained between the ring nut and the dispensing head.
The dosing chamber is defined by a deformable membrane entirely contained within the dispenser and by the dispensing head. In particular, the membrane is connected to the dispensing head at a peripheral edge and it is fastened to the ring nut at its centre.
When the user actuates the dispensing head, the membrane is deformed in such a way as to reduce the volume of the dosing chamber to dispense the product.
When the user stops acting on the dispensing head, the membrane tends to return to its original shape, favouring the return of the dispensing heat to the original position.
In other words, the membrane also serves as a return elastic means.
Known devices also comprise intake and delivery valves that regulate the flow of the fluid product respectively into and out of the dosing chamber.
In detail, during a step of aspirating the fluid product into the dosing chamber, the intake valve opens to allow the inflow of the fluid into the chamber, whilst the delivery valve remains closed to prevent the product from flowing out of the dispensing nozzle. During a step of dispensing the fluid product, vice versa, the intake valve closes and prevents the product from flowing back into the container, whilst the delivery valve opens to allow it to flow out of the dispensing nozzle.
In known devices, the intake valve is defined by a central element that shuts off a passage port between the container and the dosing chamber and that can be integrated with the membrane itself. The central element houses in a corresponding seat and it is maintained in this position by the overpressure generated while dispensing the product, whereas it is moved away from the seat by the vacuum generated during the filling of the dosing chamber.
Typically, the membrane also defines the outflow valve in combination with the dispensing head. In other words, the membrane adheres along its own edge to the dispensing head, isolating the dosing chamber during its filling.
Disadvantageously, this type of dispenser is distinguished by a limited dispensing capacity.
In detail, the dispensing capacity directly depends on the difference between the maximum volume and the minimum volume of the dosing chamber which represents the volume actually ejected during the dispensing step. Similarly, the intake capacity is also reduced for the same reasons.
Since in known dispensers the dosing chamber presents a considerable minimum volume, the dispensing capacity and the intake capacity are limited and unsatisfactory.
An additional disadvantage of this type of dispensers is associated with the fact that the outflow valve is defined by the combination of the membrane with the dispensing head. During the dispensing step, the deformed membrane can occasionally partly obstruct the outflow of the product. This drawback is further reflected in the need for a greater force on the dispensing head to obtain the outflow of the product.
Additionally, among the disadvantages associated with known dispensers there is the impossibility of achieving a delay in the closure of the outflow valve to prevent the escape of drops of product from the nozzle after the completion of the dispensing operation.
Once the dispensing operation is concluded, a minimal portion of product remains in the dispensing nozzle and can fall outwards by gravity.